{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-100664","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","state":"PUBLISHED","assignerShortName":"VulnCheck","dateReserved":"2026-09-26T02:33:59.039Z","datePublished":"2026-09-26T13:23:30.478Z","dateUpdated":"2026-09-27T16:27:49.616Z"},"containers":{"cna":{"providerMetadata":{"orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","shortName":"VulnCheck","dateUpdated":"2026-09-27T16:27:49.616Z"},"datePublic":"2026-09-10T00:00:00.000Z","title":"Netty 4.2.2 through 4.2.17 HTTP/1 Host Header Authority Confusion","descriptions":[{"lang":"en","value":"Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.2.Final through 4.2.17.Final builds the HTTP/3 :authority pseudo-header from the HTTP/1 Host header before considering the authority of an absolute-form HTTP/1 request-target. In HttpConversionUtil.toHttp3Headers(HttpMessage, boolean) — reached via Http3FrameToHttpObjectCodec(false) — a non-empty Host header takes precedence over the request-target authority, contrary to the HTTP/1.1 rule that a server receiving an absolute-form request-target must ignore the Host header. In a Netty-based HTTP/1-to-HTTP/3 gateway, proxy, or protocol bridge, a remote client can send a request such as \"GET https://trusted.example/admin HTTP/1.1\" with \"Host: attacker.example\", causing components that validate, authorize, or route on the RFC-defined request-target authority to reach a different decision than the upstream HTTP/3 peer, which receives :authority derived from the conflicting Host header. This authority confusion can affect virtual-host routing, allow-list checks, backend selection, cache keys, and URL generation. The advisory reports integrity impact only (no code execution, memory corruption, or availability impact). Fixed in 4.2.18.Final."}],"problemTypes":[{"descriptions":[{"lang":"en","description":"Improper Input Validation","cweId":"CWE-20","type":"CWE"}]}],"affected":[{"vendor":"netty","product":"netty","defaultStatus":"unaffected","packageURL":"pkg:maven/io.netty/netty-codec-http3","versions":[{"version":"4.2.2.Final","status":"affected","versionType":"custom","lessThan":"4.2.18.Final"},{"version":"4.2.18.Final","status":"unaffected","versionType":"custom"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2.2.final","versionEndExcluding":"4.2.18.final"}]}]}],"metrics":[{"format":"CVSS","cvssV4_0":{"version":"4.0","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":8.7,"baseSeverity":"HIGH"}},{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"HIGH","availabilityImpact":"NONE","baseScore":7.5,"baseSeverity":"HIGH"}}],"references":[{"url":"https://github.com/netty/netty/security/advisories/GHSA-hfr2-x62w-v49h","tags":["vendor-advisory"],"name":"GitHub Security Advisory (GHSA-hfr2-x62w-v49h)"},{"name":"VulnCheck Advisory: Netty 4.2.2 through 4.2.15 HTTP/1 Host Header Authority Confusion","tags":["third-party-advisory"],"url":"https://www.vulncheck.com/advisories/netty-4.2.2-through-4.2.15-http-1-host-header-authority-confusion"}],"credits":[{"lang":"en","value":"rexpository","type":"reporter"}],"x_generator":{"engine":"vulncheck-endgame"}}}}